1,721,247 research outputs found
Les chevaliers de Dieu
No full textD'Alessandro Vincenzo. Les chevaliers de Dieu . In: Annales de Normandie, 58ᵉ année, n°1-2, 2008. pp. 59-66
Theory of electrothermal behavior of bipolar transistors: Part I - Single-finger devices
No full textA detailed theoretical and numerical analysis of the
electrothermal behavior of single-finger bipolar transistors is proposed.
Two models of different complexities are introduced to investigate
self-heating effects in bipolar junction transistors (BJTs)
and heterojunction bipolar transistors (HBTs) biased with a constant
base–emitter voltage source or with a constant base current
source. In the constant base–emitter voltage case, simple relations
are derived for determining the onset of the flyback behavior in
the output characteristics which defines the boundary of the safe
operating region. The model indicates that the flyback behavior
disappears at high BE values, and predicts a thermal hysteresis
phenomenon at high currents. It is also shown that at high current
levels the electrothermal behavior is dominated by ohmic base
pushout. If a constant base current is applied, the model shows
that both BJTs and HBTs are unconditionally thermally stable.
The transient behavior is also considered, and the temperature
evolution is investigated for different bias conditions. The model
shows that, if the device is biased in the thermally unstable region,
thermal breakdown occurs within a finite time instant in the
limit case of a zero ballast resistance. Finally, the reduction in the
safe operating area due to avalanche effects and to the temperature
dependence of thermal conductivity is discussed, and a simplified
model is proposed
Achieving accuracy in modeling the temperature coefficient of threshold voltage in MOS transistors with uniform and horizontally nonuniform channel doping
No full text
Fast analytical modeling of dynamic thermal behavior of semiconductor devices and circuits
No full textThis paper presents a set of closed-form analytical expressions to approximate the transient solution to the heat equation without requiring any computationally intensive series summation. The parameters of these expressions can be easily extracted from the physical layout for constructing a thermal impedance matrix to be used in a self-consistent electrothermal circuit simulation of a large number of heat sources. These formulations are derived by assuming a small heat source compared to the chip area in a homogeneous chip with the boundary conditions of an adiabatic top and an isothermal bottom. The derivation allows heat sources to be located at a certain depth from the chip top. The expressions have been verified by comparison with 3-D numerical simulations
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